Screw gun

ABSTRACT

The invention relates to a screw gun including a driving unit fitted with a slidable cartridge holder adapted for receiving and indexing a separate cartridge containing a plurality of screws. The invention further relates to the replaceable cartridge containing the plurality of screws for use in a screw gun. The invention allows for the loading and insertion of a plurality of screws from a cartridge without requiring a worker to handle and insert the individual screws into the driver.

FIELD OF INVENTION

[0001] This invention relates to a screw gun. More specifically, theinvention relates to a screw gun including a driving unit fitted with aslidable cartridge holder adapted for receiving and indexing a separatecartridge containing a plurality of screws. The invention furtherrelates to the replaceable cartridge containing the plurality of screwsfor use in a screw gun. The invention allows for the loading andinsertion of a plurality of screws from a cartridge without requiring aworker to handle and insert the individual screws into the driver.

BACKGROUND OF THE INVENTION

[0002] This invention relates to a screw gun and method for loading andinserting screws. There is a need in industry for a screw gun which canload and insert a plurality of screws without a worker having toindividually handle each screw. The screw gun should be compact,lightweight and easy to use in the field. Specifically, for example, inthe heating, ventilating and air conditioning (“HVAC”) industry,hex-head self-tapping screws with integral washers, sometimes known as“tech screws”, are used for connecting adjacent sections of sheet metalduct. A majority of the time, the task of connecting these adjacentsections of sheet metal duct occurs on lifts and in confined spaces. AnHVAC worker will insert anywhere from about 2 to 10 screws per ductjoint. The present method used by the HVAC worker to insert a tech screwinvolves the use of a drill with magnetic hex socket in the drill chuckand an apron full of tech screws. The HVAC worker must pick up anindividual tech screw from his apron. He then by hand places the screwinto the hex socket, and then inserts the screw through the sections ofduct. The process is made more difficult when the worker wears gloves,not uncommon in this industry. It is estimated that up to 30% of thescrews intended to be inserted into sheet metal duct sections aredropped and lost by the worker as he or she attempts to hand place ascrew in the hex socket. Thus, the present method is laborious, slow andcostly. Accordingly, there is a need in the HVAC industry, and othersimilar industries, for a lightweight, portable screw gun that willincrease the productivity of workers and decrease costs associated withthe time consuming manual insertion of screws in the gun and the costassociated with lost screws.

[0003] Screw guns for feeding and locating fasteners for insertion intoa workpiece are generally known in the art. However, these designs arenot practical as they are overly complex and, therefore, costly, andthey are bulky and not easy to use, especially when working in confinedspaces. For example, known power operated devices for feeding andlocating fasteners, like those disclosed by U.S. Pat. No. 5,031,489 toYoung et al. and U.S. Pat. No. 5,015,127 to Hockman, require that afastener driver be connected to an air supply to power the device andconnected to a hopper or the like in order to continuously feed thedriver with fasteners. Such devices limit their application because oftheir lack of mobility and unwieldiness. Accordingly, such devices arenot practical for use in confined spaces, such as when working on ascaffolding or a lift. Similar devices for feeding and locatingfasteners have strips which carry the screws and are swingedly suspendedfrom the device, such as disclosed in U.S. Pat. Nos. 3,910,324 toNasiatka and 4,581,964 to Takatsuru. These devices are also notpractical for use in confined spaces because of the added weight andawkwardness associated with the devices.

[0004] U.S. Pat. No. 4,936,169 to Parsons discloses a portable devicefor positioning and inserting fasteners wherein an applicator ispositioned adjacent to a positioning mechanism containing a rotatablecylinder which includes a plurality chambers for housing fasteners.However, the Parsons device also includes a number of drawbacksincluding that it is bulky, the operator is required to align a screwwith the applicator by hand before he can insert a second screw into aworkpiece, and the screw is not readily visible prior to insertion.

[0005] The present invention solves the problems of the prior artdevices as discussed hereafter.

PRIMARY OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION

[0006] It is a primary object of the invention to provide a screw guncapable of carrying a number of screws in an easily loadable andremovable cartridge, thereby allowing a worker the ability to insertmultiple screws in a workpiece without ever having to handle theindividual screws.

[0007] It is a further primary object of the invention to provide acartridge for carrying a multiplicity of fasteners, such as screws,which is easily loaded and removed from a screw gun. The fasteners arereleasably held in the cartridge until engaged by the driver of thescrew gun.

[0008] It is a further primary object of the invention to provide ascrew gun for inserting fasteners, such as screws, having a novelcartridge holder for locating the fasteners from a cartridge into thedriver of the screw gun.

[0009] It is a further object of the invention to provide a screw gunhaving a driver and guide post with a cartridge holder slidably arrangedthereon for carrying a rotatable cartridge containing a multiplicity ofscrews. The screw gun components cooperate with the cartridge forquickly and efficiently locating fasteners, such as screws, on thedriver for subsequent insertion into a workpiece.

[0010] It is another object of the invention to provide a screw gunhaving a cartridge holder which will automatically align a cartridgecontaining a multiplicity of fasteners, such as screws, so that a workercan easily and quickly change the cartridge in the screw gun. Thecartridge upon insertion into the gun will automatically be aligned forlocating and loading a fastener.

[0011] It is another object of the invention to provide a screw gunhaving a cartridge holder which will automatically index and align acartridge containing a multiplicity of fasteners, such as screws, bypump action so that a worker can easily and quickly insert a number offasteners from the cartridge without having to handle the individualfasteners or adjust the cartridge.

[0012] It is another object of the invention to provide a screw gunwhich is simple in construction, easy to manufacture and durable. Thescrew gun is light-weight, portable and can be used in confined spaces,such as on a lift, to insert tech screws in duct work. The inventionprovides for an easily loadable and unloadable cartridge holding 8 to 10screws.

[0013] It is another object of the invention to provide a screw gunhaving a driver that projects sufficiently beyond the cartridge holdersuch that the screw is plainly visible to the worker for easily locatingthe position of the screw into the workpiece.

[0014] It is a further object of the invention to provide a screw gunhaving the driver projecting beyond the cartridge holder to allowinsertion of screws in tight spaces.

[0015] It is another object of the invention to provide a screw gunwhere the center of the gravity of the gun remains close to a worker'swrist to make the gun easy to hold and well balanced. This provides ascrew gun which is easy and comfortable to use for the worker.

[0016] The screw gun of the present invention comprises a driving unit;an elongated driver for receiving a fastener such as a screw; a guidepost connected to the driving unit and having a cam path; a cartridgeholder slidably mounted on the guide post in cooperation with the campath of the guide post, and a cartridge carrying a multiplicity offasteners. In this specification, the fasteners will hereafter bereferred to as screws with the understanding that other fasteners may beused with the invention.

[0017] In operation, the screw cartridge is inserted into the cartridgeholder of the gun and it is automatically aligned so that a chamber ofthe cartridge is in alignment with the driver of the gun. A screw isloaded from the cartridge to the driver by pump action. By pump action,we mean that the cartridge holder is manually moved inward toward thegun to load a screw into the driver and for subsequent insertion into aworkpiece. The cartridge holder includes a cam follower which moves incooperation with the cam path on the guide post. The inward movement ofthe cartridge holder causes an indexing mechanism in the cartridgeholder to be in position, or “cocked”, to index the next chamber of thecartridge with the driver when the cartridge holder is thereafter pumpedoutward after insertion of the screw. Thus, after a screw is inserted,the cartridge holder is moved outward which, at the end of the outwardstroke, causes the cocked indexing mechanism to rotate the cartridgesuch that the next screw is in alignment with the driver. It isunderstood that the pump action of the screw gun may be replaced by anautomated system such as using a spring means connected to the cartridgeholder and the driver to allow the cartridge holder to automaticallyreturn to the outer end of the driver after insertion of a screw.

[0018] The present invention includes a unique cartridge for holding amultiplicity of screws, preferably eight to ten screws. The worker doesnot have to handle the individual screws and merely inserts thecartridge into the screw gun and removes the cartridge when expended. Acartridge of eight to ten screws can be inserted quickly providing easeof use, saving substantial time to the worker, avoiding the handling ofindividual screws, and avoiding the loss of screws. The cartridgeincludes a central opening through which the guide post passes and amultiplicity of chambers for carrying the screws. Extending outwardlybetween each chamber is a rib which serves to align and index thecartridge in cooperation with a pin and a pawl of an indexing mechanismof the cartridge holder as will be explained below.

[0019] Each chamber of the cartridge includes a screw retaining portionand an exit portion through which a screw is eventually moved intoreadiness for insertion. Flexibly attached near the exit portion of thecartridge chamber are a multiplicity of fingers adapted for retainingthe screw. Each finger has a free end and a bound end. The bound end isthat part of finger that is flexibly attached near the exit portion ofthe chamber. The retaining portion fingers include a groove adapted toreceive an integral washer of the screw. The groove is interposedbetween a first tapered portion and a second tapered portion. The firsttapered portion is adjacent to the head of the screw while the secondtapered portion is positioned just underneath the groove which holds theretained washer.

[0020] The design of the chambers of the cartridge is such that when thedriver is inserted into the retaining portion of the chamber during thepump action of the cartridge holder, the driver rides along the firsttapered portion of the fingers exerting outward pressure thereon as thedriver moves over the head of the screw. The pressure exerted on thefirst tapered portion causes the washer to become dislodged from thegroove by forcing the second tapered portion outward. When the cartridgeholder completes the inward pumping motion, the loaded screw is fullyvisible to the worker and ready to be inserted into a workpiece.

[0021] The cartridge holder of the present invention comprises a housinghaving a rear cover plate, a front cover plate and a pocket forreceiving the screw cartridge. The pocket includes an inner pocket wallbehind which is an indexing mechanism for aligning and indexing thescrew cartridge. The pocket is adapted to receive the screw cartridgeand, in conjunction with the indexing mechanism, to align a chamber ofthe cartridge with the driver. Thus, a chamber of the cartridge isautomatically aligned with the driver by means of an interaction betweentwo ribs of the cartridge and a pin and a pawl assembly of the indexingmechanism which extend through the inner pocket wall into the pocket ofthe cartridge holder. The pin and pawl are aligned essentially on adiameter of the cartridge. More specifically, the pin and pawl areoffset from the center line of the cartridge by half of the thickness ofthe ribs of the cartridge so that the ribs lay over the center line insuch a way as to align a chamber of the cartridge with the driver.

[0022] The indexing mechanism of the cartridge holder is of simpleconstruction so as to include minimal moving parts and to be durable. Itfunctions to align the cartridge when it is inserted into the cartridgeholder and to index the cartridge. The indexing mechanism comprises asleeve through which the guide post extends. A cam follower extends intothe sleeve and cooperates with the cam path of the guide post. Extendingfrom the sleeve are an oscillating plate and a cam plate. Theoscillating plate includes a housing carrying the pawl which pawlextends through the inner pocket wall and into the pocket. The openingin the inner pocket wall through which the pawl extends is in an arcuateshape. The oscillating plate further includes a post to which a springis connected. The opposite end of the spring is connected to a secondpost attached to the underside of the inner pocket wall. The cam plateis sloped and cooperates with a cam follower at one end of the pin.

[0023] The indexing mechanism is caused to rotate when the cartridgeholder is pumped inwardly toward the driving unit as the cam follower ofthe indexing mechanism rides along the cam path of the guide post.During this rotation, the oscillating plate is rotated and causes thepawl to move through the arcuate opening in the inner pocket wall andprovides tension to the spring. A sloped portion of the head of the pawlpasses under the next rib of the cartridge holder. After passing underthe rib, the non-sloped side of the pawl head engages the rib and thetension from the spring holds it against the rib. At this point, thecartridge is not free to rotate because the driver has passed through achamber of the cartridge. Concurrently, the cam plate is rotated alongthe cam follower portion of the pin causing the pin to move inwardly andout of the pocket of the cartridge holder. This motion of the indexingmechanism serves to cock the cartridge holder for subsequent indexing ofthe screw cartridge when the cartridge holder is moved outward. Thus,the pin has been moved out of the pocket allowing for the ribs of thescrew cartridge freedom to rotate. When the cartridge holder is movedoutward the pawl moves back to its original position during whichmovement its engagement with the rib of the cartridge thereby moves thecartridge to index the next screw chamber in alignment with the driver.At the end of this movement, the pin is moved back into the pocket bymeans of the cam plate and cam follower of the pin. The pin again nowserves to engage a rib of the cartridge, thereby stopping the rotationof the cartridge and automatically aligning a chamber of the cartridgewith the driver for subsequent loading of the next screw from thecartridge.

[0024] The cam path of the guide post includes a gradual spiral at aside wall against which the cam follower of the indexing mechanism ridesduring the inward pumping action of the cartridge holder. Generally, themovement of the cam follower against the side wall by way of the pumpaction of the cartridge holder is translated through the indexingmechanism located within the cartridge holder into rotatably indexingthe cartridge as generally described above and specifically describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other objects, advantages, and novel features of the presentinvention will become apparent from the following detailed descriptionof the invention when considered in conjunction with the accompanyingdrawings, in which like reference numerals designate like partsthroughout the figures thereof, and wherein:

[0026]FIG. 1 is a side elevational view of a screw gun in accordancewith a preferred embodiment of the present invention;

[0027]FIG. 2 is a side partial sectional view of the screw gun of thepresent invention in the unloaded position;

[0028]FIG. 2A is a vertical cross-sectional view at line 2A-2A of FIG.1;

[0029]FIG. 3 is a side partial sectional view of the screw gun of thepresent invention with a screw loaded in the driver and ready forinserting the screw into a workpiece;

[0030]FIG. 4 is a top plan view of a preferred embodiment of the screwgun of the present invention;

[0031]FIG. 5 is a cross-sectional view of the cartridge holder at line5-5 of FIG. 2 when the gun is in the unloaded position;

[0032]FIG. 6 is a cross-sectional view of the cartridge holder at line6-6 of FIG. 3 when the gun is in the loaded position;

[0033]FIG. 6A is a perspective view of the indexing mechanism;

[0034]FIG. 7 is a view along line 7-7 in FIG. 5 of the indexingmechanism of the cartridge holder in the unloaded position;

[0035]FIG. 7A is a perspective view of the pin and cam follower of thepin;

[0036]FIG. 8 is a view along line 8-8 in FIG. 6 of the indexingmechanism of the cartridge holder in the loaded position;

[0037]FIG. 9 is a cross-sectional view of the cartridge holder andcartridge at line 9-9 of FIG. 2;

[0038]FIG. 9A is a schematic showing the location of the pin and pawl inrelation to the center line of the cartridge for aligning the cartridge;

[0039]FIG. 10 is a front elevational view of the screw gun of thepresent invention;

[0040]FIG. 11 is a bottom view of the guide post showing the cam path;

[0041]FIG. 12 is a cross-sectional view at line 12-12 of FIG. 11;

[0042]FIG. 13 is a cross-sectional view at line 13-13 of FIG. 11;

[0043]FIG. 14 is a front elevational view of the screw cartridge of thepresent invention;

[0044]FIG. 14A is a view at line 14A-14A of FIG. 14 showing a rib of thescrew cartridge;

[0045]FIG. 15 is a cross-section of the screw cartridge at line 15-15 ofFIG. 14, and

[0046]FIG. 16 is a sectional view of a chamber of the screw cartridge.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0047] An improved screw gun and parts thereof for inserting fastenerssuch as screws is shown in FIGS. 1 through 16. The screw gun 8 generallycomprises a driving unit 10 having a cover plate 12, a driver 14, aguide post 16, a cartridge holder 18 and a cartridge 20. The cartridgeholder 18 is slidably affixed to guide post 16 and adapted to align andindex the cartridge 20 which contains a plurality of chambers 22 forretaining screws 24. The screws 24 are loaded on the driver 14 by meansof a pump action of cartridge holder 18 along a cam path 80 on guidepost 16. Thus, FIG. 2 shows the screw gun in the unloaded position. Whenthe cartridge holder 18 shown in FIG. 2 is pumped along the cam path 80of guide post 16, the screw gun is loaded with a screw as shown in FIG.3. As will be explained in greater detail hereafter, when the cartridgeholder is pumped, a screw is loaded onto the driver 14 and the indexingmechanism shown in FIGS. 5-8 is cocked to index the cartridge 20 whenthe cartridge holder 18 is moved outward from the position in FIG. 3 tothe position in FIG. 2 in preparation for loading the next screw.

[0048] Driving unit 10 is a conventional driving device used in knownscrew guns and drills such as a Black & Decker drill or a Makita drill.Driver 14 is also similar to drivers used in conventional screw guns,except that it is slightly longer in the preferred embodiment tofacilitate acceptance of the cartridge holder 18 and to providevisibility beyond the cartridge holder. Driver 14 includes a driversocket 26 at its end for receipt of a fastener 24, in this instance ahex head screw, although other fasteners may also be used with theinvention. In a preferred embodiment, driver socket 26 is magnetic andincludes an indented portion 27 which mates with the hex head of screw24. It is understood that indent 27 of driver socket 26 may be any shapeor depth to allow for the receipt of numerous different screw shapes. Inthe alternative, different shaped detachable driver sockets may be usedto accommodate different shaped fastener heads.

[0049] Cover plate 12 covers the operating portion of the driving unit10 and includes an opening for driver 14. It is made of any suitablematerial, such as plastic or metal, and is held in place by any suitablefastening means such as screws.

[0050] Guide post 16 extends outwardly from cover plate 12 and isattached to cover plate 12 by any suitable fastening means such asscrews. In the alternative, guide post 16 may be part of cover plate 12.Guide post 16 includes a path 42, e.g. FIG. 2, for maintaining cartridgeholder 18 on the guide post 16 as discussed in greater detail below.Guide post 16 further includes a cam path 80, e.g. FIG. 11, whichcooperates with a cam follower 76 in cartridge holder 18 in the indexingand alignment of cartridge 20 as will also be explained in greaterdetail below. In the preferred embodiment, the guide post 16 is locatedin approximately the center of driving unit 10. However, this is notlimiting to the invention as it is understood that the guide post 16, ormultiple guide posts, may be positioned at different locations ondriving unit 10.

[0051] Additionally, when the screw gun is in the loaded position, e.g.FIG. 3, the guide post is shown extending beyond the front part of thecartridge holder. In another embodiment, the guide post is made of alength such that it is flush with the cartridge holder when the screw isin the loaded position as discussed below.

[0052] Cartridge holder 18, as shown for example in FIGS. 1 through 4,includes a housing 28 having a rear cover plate 30 and a front coverplate 32. The cartridge holder is made of any suitable lightweight anddurable material, preferably plastic. Rear cover plate 30 includes adriver passage 34 and a guide post passage 36 through which driver 14and guide post 16, respectively, pass through. The cartridge holder 18includes a pocket 48 for receiving the screw cartridge 20. The front andrear cover plates are attached to the housing by screws or any othersuitable fastening means. In the alternative, the front cover plate 32may be integral with the housing 28.

[0053] Pocket 48 includes an inner pocket wall 50 having passages 34 and36 for driver 14 and guide post 16, respectively. An indexing mechanism51 is constructed and arranged in the space between inner pocket wall 50and rear cover plate 30 as discussed in greater detail below. Innerpocket wall 50 further includes an arcuate opening 60 through which pawl56 extends and moves and an opening 59 through which a pin 58 extends,as also discussed in greater detail below. Suitable sealing means may beprovided at these openings in wall 50 to avoid contamination of thespace between wall 50 and plate 30.

[0054] To prevent over-extension of cartridge holder 18 on guide post 16or disengagement of cartridge holder 18 from the screw gun, a slidescrew 38, as shown in FIG. 2A, is inserted into a slide screw passage 40in cartridge holder 18. Slide screw 38 is adapted to ride within thepath 42 (FIG. 2) in guide post 16 and having stop means 44 and 46. Path42 thereby limits the distance of movement of cartridge holder 18 onguide post 16. In the alternative, cartridge holder 18 may be retainedon guide post 16 by a cap on the end of the guide post. This willeliminate the need for slide screw 38 and path 40 and path 42.

[0055] As referred to above, cartridge holder 18 includes a pocket 48for receiving cartridge 20. When cartridge 20 is inserted into pocket48, it is automatically aligned so that a chamber 22 is aligned in frontof driver passage 34. More particularly, cartridge 20 includes anopening 54 though which guide post 16 passes and ribs 52 betweenchambers 22 and extending outwardly therefrom at the front of thecartridge, e.g. FIG. 14A. As shown for example at FIG. 9, alignment of achamber 22 with driver passage 34 is achieved by means of an interactionbetween a rib 52 with pawl 56 of cartridge holder 18 and pin 58 withanother rib 52. Pawl 56 and pin 58 extend through inner pocket wall 50into pocket 48 and are positioned approximately diametrically opposed toeach other and offset by the radius of the pin and half the thickness ofthe rib as shown by way of illustration in the schematic of FIG. 9A.Thus, when a cartridge 20 is inserted into cartridge holder 18,cartridge 20 will always come to rest within pocket 48 with a chamber 22in alignment with driver passage 34. This is important as anytime aworker inserts a new cartridge 20 into the screw gun, a screw isautomatically aligned with the driver 14 and there is no need forfurther manipulation by the worker, saving time and making the gunsimpler and easier to use.

[0056] The mechanism for indexing the cartridge 20 within cartridgeholder 18 and aligning the screws of the cartridge with the driver 14will now be explained in greater detail. In the space between rear coverplate 30 and inner pocket wall 50 is indexing mechanism 51. The indexingmechanism 51 includes a sleeve 53 through which guide post 16 passes.Connected to the sleeve 53 is an oscillator plate 62. Oscillator plate62 includes a pawl assembly 63. Pawl assembly 63 includes a housing 65which has a compression spring (not shown) contained therein. Thecompression spring is held in place by a retaining pin (not shown) whichpasses through housing 65. The compression spring permits the pawl 56 tobe depressed when loading a screw when oscillator plate 62 is rotated.The head of pawl 56 is sloped to allow it to easily pass under bycompression an adjacent rib 52 a when oscillating plate 62 is rotatedfrom the unloaded to the loaded position. After pawl 56 passes under therib 52 a, the compression spring moves the pawl back into the pocket andthe unsloped side of the pawl head engages the rib 52 a. When oscillator62 plate is reversed in rotation the opposite side of the pawl head willmove the rib 52 a to index the cartridge as discussed in further detailbelow.

[0057] Oscillating plate 62 further includes a post 70 connected theretoand receives spring 68. Spring 68 is connected at its other end to asecond post 72 which is connected to the underside of inner pocket wall50.

[0058] Pawl 56 extends resiliently outwardly into pocket 48 through thearcuately shaped slot 60 in inner pocket wall 50. Slot 60 includes atone end a stop 66 and at the other end an end wall 64. Stop 66 islocated where it is diametrically opposite to pin 58 to stop pawl 56, tothereby properly position the pawl to allow for automatic alignment ofcartridge 20. The pawl 56 will not normally engage end wall 64 whenoscillator plate 62 is rotated.

[0059] Sleeve 53 further includes a sloped cam plate 78 which cooperateswith a cam follower 74 at the end of pin 58 to provide the in and outmotion of pin 58 through inner pocket wall 50. Thus, when indexingmechanism 51 is rotated from the unloaded position (FIG. 7) to theloaded position (FIG. 8), the pin 58 will move inward by means of themovement of cam plate 78 along cam follower 74.

[0060] Sleeve 51 further includes a cam follower 76 which is on theinside of sleeve 53. Cam follower 76 may be a screw which extendsthrough sleeve 53 and is held in place by a nut 77 at its opposite end.As described in further detail below, cam follower 76 moves along campath 80 of guide post 16.

[0061] Referring now to FIGS. 11 through 13, cam path 80 includes agradual spiral 88 along side wall 82 of the path against which camfollower 76 rides when cartridge holder 18 is pumped inwardly and whichprovides tension to the spring 68 as pawl 56 picks up the next rib 52 a.Spring 68 assures that cam follower 76 is kept in contact with side wall82 throughout the inward pumping motion of cartridge holder 18. When thecartridge holder 18 is moved outwardly, the cam follower 76 is retainedalong wall 84 of cam path 80 by virtue of pawl 56 being trapped behindthe next adjacent rib 52 a of the cartridge until the end of cam path 80is reached where the cartridge is free to rotate and the cam followermoves over to wall 82.

[0062] More particularly, as shown for example at FIGS. 2, 5 and 7, whenthe screw gun is in the unloaded position, cam follower 76 is positionedat an outer end 90 of guide post 16 such that cam follower 76 is locatedat spiral portion 88 of cam path 80. In this position, pawl 56 is atstop 66 of path 60. As cartridge holder 18 is pumped inwardly, driver 14moves through pocket 48 of housing 28 and enters a chamber 22 ofcartridge 20 whereby a screw 24 is loaded in driver socket 26.Simultaneously, cam follower 76 rides up side wall 82 of cam path 80 ofguide post 16 towards parallel portion 86 at the end of the cam path.The movement of cam follower 76 against side wall 82 by way of theinward pumping of cartridge holder 18 is translated through the indexingmechanism 51 which will be in the loaded position as shown in FIGS. 3, 6and 8 and ready to index cartridge 20 when the cartridge holder 18 ismoved outwardly.

[0063] Further, as cam follower 76 moves along wall 82 of guide post 16,cam plate 78 is partially rotated around guide post 16 and thereby alsomoving oscillator plate 62 in the same direction as cam follower 76.Consequently, pawl 56 is rotated along with oscillating plate 62 andpositioned behind the adjacent rib 52 a, and pin 58 is pulled inwardlyout of pocket 48. At this point, cartridge holder 18 is cocked, ready toindex another chamber 22 into alignment with driver 14 when thecartridge holder 18 is pumped outward.

[0064] Now, after driving a screw, cartridge holder 18 is moved backtoward end 90 of guide post 16. In turn, cam follower 76 rides alongside wall 84 of cam path 80 until slide screw 38 contacts stop 46. Camfollower 76, however, is prevented from riding along side wall 82because of the interaction of pawl 56 with the rib 52 a. The newlypositioned indexing pawl 56 now exerts pressure against rib 52 a becauseof the tension produced in spring 68 when oscillating plate 62 is movedaway from post 72. However, until driver 14 is completely withdrawn fromchamber 22, cartridge 20 cannot rotate around guide post 16 and alignthe next screw with driver 14. When driver 14 is completely withdrawnfrom chamber 22, the physical hindrance preventing movement of pawl 56is removed, and pawl 56 is sprung back to stop 66 thereby indexingcartridge 20 to place a new chamber 22 in alignment with driver 14. Thecartridge is prevented from rotating too far as pin 58 is moved backinto pocket 48 by means of cam plate 78 to stop the next rib 52.

[0065] Referring now to FIGS. 14 through 17, each chamber 22 ofcartridge 20 generally includes a screw retaining portion 94, and anexit portion 96 through which a hex-head screw 24 having an integralwasher 100 is driven by driver 14. Flexibly attached near to exitportion 96 of chamber 22 is a set of three fingers 102 adapted at oneend for retaining screw 24. Each finger 102 has a free end 104 and abound end 106. Bound end 106 is that part of finger 102 that is flexiblyattached near to exit portion 96 of the cartridge. The cartridge 20 isintended to be disposable and is made of plastic, e.g., polyvinylchloride, although the cartridge may be made of other materials or madeto be reusable.

[0066] Fingers 102 include a groove 108 adapted to receive washer 100 ofscrew 24. Groove 108 is interposed between a first tapered portion 110and a second portion 112. First tapered portion 110 is adjacent to thehead of screw 24 while second tapered portion 112 is positionedunderneath groove 108 which holds retained washer 100 of screw 24. Thesecond portion 112 serves to aid in holding the screw in the cartridgeuntil the screw is engaged by the driver as discussed below.

[0067] When driver 14 is inserted into chamber 22 during the pumpingaction, the driver socket 26 rides along first tapered portion 110exerting outward pressure thereon as socket 26 with indent 27 moves overthe head of screw 24. The pressure exerted on first tapered portion 110causes washer 100 to become dislodged from groove 108 by forcing secondtapered portion 112 of finger 102 outward. The driver 14 then passesthrough exit portion 96 and outside of cartridge 20 as shown in FIG. 3.Screw 24 is now located in driver socket 26 and ready to be insertedinto workpiece 120. It is noted that the screw 24 is plainly visible tothe worker to allow easy positioning of the screw in the workpiece.

[0068] Having described the presently preferred embodiment, the screwgun is operated as follows. In operation, cartridge 20 containing screws24 is inserted into cartridge holder 18 by the worker. Cartridge 20automatically aligns itself such that a chamber 22 is positioned infront of driver passage 34 and driver 14. Cartridge holder 18 is thenpumped inwardly toward cover plate 12. During this pumping action, threeoperations are taking place. One, the screw is placed in the driversocket 26; two, the screw is released from the fingers 102 in thecartridge, and three, the charging of the indexing spring 68 takesplace. Thus, during the initial pumping of the cartridge, the driversocket 26 of driver 14 engages the head of screw 24. Pressure is appliedto the fingers 102 of the cartridge 20 and the fingers extend outwardlythereby releasing the screw 24 from the cartridge and the driver 14continues to pass through and out of the cartridge 20. During thepumping action, the cam follower 76 of indexing mechanism 51 slidesalong cam path 80 of the guide post 16. This pumping action causes theoscillating plate 62 to rotate. During this rotation, pawl 56 is movedalong arcuate path 60, spring 68 being extended during such movement,and the sloped head of pawl 56 is compressed and passes under the nextrib 52 a and upon doing so the pawl pops back up on the opposite side ofrib 52 a and the head of pawl 56 engages rib 52 a under tension fromspring 68. During this motion pin 58 is moved out of pocket 48 byrotation of cam plate 78 along cam follower 74 of pin 58. The device isnow charged to index the next screw into position. After driving screw24 into the workpiece, cartridge holder 18 is manually pumped outwardlythereby withdrawing driver 14 from cartridge 20. Withdrawal of driver 20allows spring loaded pawl 56, which was cocked during the inward strokeof cartridge holder 18, to advance thereby aligning the next chamber 22containing a screw 24 with driver passage 34. The cartridge cannotadvance beyond the chamber because the rib 52 of the cartridge isstopped at pin 58 which has moved back into the pocket by means of camplate 78.

[0069] While not necessary or limiting to the invention, it has beenfound that the screw is most easily loaded in the driver 14 if thedriver 14 is being slowly rotated by the driving unit. This can be donemanually by the worker or the screw gun can include means forautomatically rotating the driver at a slow speed. In the latter case,the rotation may be fixed at a slow speed by means of a stop mechanismin the trigger of the driving unit which stop can be overrode byapplying additional pressure on the trigger after the screw is loaded.In the alternative, a rheostat switch can be associated with themovement of the cartridge holder such that when the cartridge holderbegins its movement away from the driving unit the driver beginsrotation at a slow speed.

[0070] Additional modifications to the above screw gun are alsoenvisioned. For example, as referred to previously, the guide post 16can be modified such that it is of shorter length so as to be flush withthe cartridge holder when the gun is in the loaded position. In thisembodiment, the cam follower 76 of the cartridge holder is moved furtherout in the sleeve 53 of the indexing mechanism 51. As also referred toabove, a cap can be placed at the end of the guide post to stop themovement of the cartridge holder to preclude the need for path 42 andslide screw 38 and path 40. Also, the location of the pin and pawl canbe reversed or otherwise modified.

[0071] It is also understood that other equivalent means may be used toindex and align the cartridge. Thus, the above-described inventionprovides for cooperation between the cartridge and the cartridge holderin aligning and indexing the cartridge. Other equivalent means otherthan as above disclosed may be used for this alignment and indexing andthe invention is not limited to the presently preferred means definedabove. For example, a ratchet system may be used wherein the cartridgeserves as a toothed wheel and ratchets on the cartridge holder to alignand index the cartridge.

[0072] While a preferred embodiment of the screw gun has been describedin detail above, various modifications and variations of the inventionare possible in light of the above teachings. For example, while theindexing mechanism described above is the presently preferred means ofindexing and aligning a screw within the driver, a different indexingmechanism may be used. Similarly, while the invention is discussed interms of inserting hex-head screws, the invention may be used with othertypes of fasteners. Further, the screw gun may be completely automatedby a separate power source or by imposing the pumping action by virtueof driving a screw with a spring mechanism moving in while driving thescrews. It is, therefore, to be understood that within the scope of theappended claims the invention may be practiced otherwise than asabove-described.

It is claimed:
 1. A screw gun for driving a fastening means comprising:a driving unit having a driver and a guide post connected thereto, acamming means located on said guide post, a cartridge holder slidablyaffixed to said guide post and constructed to receive a cartridgecontaining a plurality of fastening means.
 2. A screw gun in accordancewith claim 1 further comprising a cartridge rotatably supported by saidcartridge holder.
 3. A screw gun in accordance with claim 2 wherein saidcartridge comprises a rotatable housing having a plurality of chambersfor releasably holding said fastening means and having a means forindexing said cartridge.
 4. A screw gun in accordance with claim 3wherein said indexing means further aligns said cartridge in saidcartridge holder.
 5. A screw gun in accordance with claim 3 wherein saidindexing means comprises outwardly extending ribs between each of saidchambers.
 6. A screw gun in accordance with claim 5 wherein saidchambers include a plurality of fingers for releasably holding saidfastening means.
 7. A screw gun in accordance with claim 6 wherein saidfingers have a free end and a bound end.
 8. A screw gun in accordancewith claim 7 wherein said fingers include of first tapered portion and asecond tapered portion constructed and arranged for holding saidfastening means.
 9. A screw gun in accordance with claim 8 wherein saidfingers further include a groove between said first and second taperedportions.
 10. A screw gun in accordance with claim 9 further including aplurality of fasteners in said cartridge.
 11. A screw gun in accordancewith claim 10 wherein said fasteners are hex-head screws.
 12. A screwgun in accordance with claim 3 further comprising a plurality offasteners in said cartridge.
 13. A screw gun in accordance with claim 12wherein said fasteners are hex-head screws.
 14. A screw gun inaccordance with claim 1 wherein said driver includes a socket for matingwith the head of said fastening means.
 15. A screw gun in accordancewith claim 14 wherein said fastening means is a hex-head screw.
 16. Ascrew gun in accordance with claim 1 wherein said cartridge holdercomprises a housing having a front cover plate, a rear cover plate, anda pocket in said housing for receiving a cartridge having a plurality offastening means.
 17. A screw gun in accordance with claim 16 whereinsaid pocket further includes an inner pocket wall and said inner pocketwall having an indexing means connected thereto and constructed andarranged for communication with said camming means in said guide post.18. A screw gun in accordance with claim 17 wherein said indexing meanscomprises a sleeve having a cam follower.
 19. A screw gun in accordancewith claim 17 wherein said indexing means comprises a sleeve having acam follower, an oscillating plate and a cam plate.
 20. A screw gun inaccordance with claim 19 wherein said indexing means further includes apawl means housed in said oscillating plate and a spring meansconstructed and arranged for controlling rotation of said oscillatingplate.
 21. A screw gun in accordance with claim 17 wherein said indexingmeans includes a pin means and a pawl means for automatically aligningsaid cartridge in said screw gun.
 22. A screw gun in accordance withclaim 17 wherein said indexing means comprises a sleeve through whichsaid guide post passes through, a cam follower which cooperates withsaid caming means of said guide post, and a pin means and a pawl meanswhich extend through said inner pocket wall into said pocket wherebysaid indexing means function to automatically align said cartridge andto index said cartridge.
 23. A screw gun in accordance with claim 17further comprising a cartridge rotatably supported by said cartridgeholder.
 24. A screw gun in accordance with claim 23 wherein saidcartridge comprises a rotatable housing having a plurality of chambersfor releasably holding a fastening means and having an outwardlyextending rib between each of said chambers.
 25. A screw gun inaccordance with claim 24 wherein said chambers include a plurality offingers for releasably holding said fastening means.
 26. A screw gun inaccordance with claim 25 wherein said fingers include of first taperedportion and a second tapered portion constructed and arranged forholding a fastener.
 27. A screw gun in accordance with claim 26 furthercomprising a groove between said first and second tapered portions. 28.A screw gun in accordance with claim 27 further comprising a pluralityof fasteners in said cartridge.
 29. A screw gun in accordance with claim28 wherein said fasteners are hex-head screws.
 30. A screw gun inaccordance with claim 23 wherein said cartridge includes a plurality offasteners.
 31. A screw gun in accordance with claim 30 wherein saidfasteners are hex-head screws.
 32. A screw gun having a cartridge holderand a rotatable cartridge for insertion therein said cartridgecomprising a housing having a plurality of chambers for releasablyholding a fastening means and having means for indexing said cartridgein said cartridge holder.
 33. A screw gun in accordance with claim 32wherein said means for indexing said cartridge comprises an outwardlyextending rib extending between each of said chambers.
 34. A screw gunin accordance with claim 32 wherein said means for indexing saidcartridge comprises a ratcheting means.
 35. A screw gun in accordancewith claim 32 wherein said chambers include a plurality of fingers forreleasably holding said fastening means.
 36. A screw gun in accordancewith claim 35 wherein said fingers further include a first taperedportion and a second tapered portion constructed and arranged forholding a fastener and a groove between said first and second taperedportions.
 37. A screw gun in accordance with claim 36 further includinga plurality of fasteners in said cartridge.
 38. A screw gun inaccordance with claim 37 wherein said fasteners are hex-head screws. 39.A screw gun in accordance with claim 32 further including a plurality offasteners in said cartridge.
 40. A screw gun in accordance with claim 39wherein said fasteners are hex-head screws.
 41. A screw gun inaccordance with claim 32 wherein said cartridge has eight chambers. 42.A screw gun in accordance with claim 32 wherein said cartridge has tenchambers.
 43. A screw gun in accordance with claim 32 wherein saidcartridge is made from plastic.
 44. A screw gun having a cartridgeholder for supporting and indexing a cartridge containing a plurality ofchambers for fastening means, said cartridge holder having: a pocketadapted for supporting said cartridge, a passage for receiving a driverof said screw gun, and means for aligning a chamber of said cartridgewith said driver passage.
 45. A screw gun in accordance with claim 44wherein said means for aligning a chamber of said cartridge with saiddriver passage comprises a pin means and a pawl means.
 46. A screw gunin accordance with claim 45 wherein said cartridge holder furtherincludes a means for indexing said cartridge within said cartridgeholder.
 47. A screw gun in accordance with claim 46 wherein saidcartridge holder further includes a front cover plate and a rear coverplate.
 48. A screw gun in accordance with claim 47 wherein said pocketis defined by said front cover plate and an inner pocket wall.
 49. Acartridge for a screw gun comprising a rotatable housing having aplurality of chambers for releasably holding a fastening means andhaving means for indexing the cartridge in a cartridge holder.
 50. Acartridge in accordance with claim 49 wherein said means for indexingthe cartridge in the cartridge holder comprises an outwardly extendingrib between each of said chambers.
 51. A cartridge in accordance withclaim 50 wherein said chambers include a plurality of fingers forreleasably holding said fastening means.
 52. A cartridge in accordancewith claim 51 wherein said fingers have a free end and a bound end. 53.A cartridge in accordance with claim 52 wherein said fingers include offirst tapered portion and a second tapered portion constructed andarranged for holding said fastener means.
 54. A cartridge in accordancewith claim 53 wherein said fingers further include a groove between saidfirst and second tapered portions.
 55. A cartridge in accordance withclaim 54 further including a plurality of fasteners in said cartridge.56. A cartridge in accordance with claim 55 wherein said fasteners arehex-head screws.
 57. A cartridge in accordance with claim 49 whichfurther includes a plurality of fasteners in said cartridge.
 58. Acartridge in accordance with claim 57 wherein said fasteners arehex-head screws.
 59. A method of loading a fastening means into a driverof a screw gun having a cartridge holder, said method comprising thesteps of: inserting a cartridge having a plurality of chambers withfastening means therein into the cartridge holder slidably attached tosaid screw gun, and aligning a first chamber of said cartridge with saiddriver through an interaction between an indexing means of saidcartridge holder with an indexing means of said cartridge, and pumpingsaid cartridge holder, thereby loading a fastening means from said firstchamber into said driver.
 60. The method of claim 59 wherein saidcartridge includes a rotatable housing having a plurality of chambersfor releasably holding said fastening means and means for indexing saidcartridge.
 61. The method in accordance with claim 60 wherein said meansfor indexing said cartridge comprises an outwardly extending rib betweeneach of said chambers.
 62. The method in accordance with claim 59wherein said indexing means comprises a pawl means and a pin means. 63.The method in accordance with claim 59 wherein during the pumping of thecartridge holder the driver passes through the cartridge and preventsrotation of the cartridge and provides a means for cocking the indexingmechanism to load a second fastening means.
 64. A method of inserting afastening means into a work piece from a screw gun, said methodcomprising the steps of: inserting a cartridge containing a plurality offastening means into a cartridge holder of said screw gun; automaticallyaligning a chamber of said cartridge with a driver of said screw gun;inserting a fastening means from said cartridge into said driver bypumping said cartridge holder; and inserting said fastening means into aworkpiece.
 65. The method in accordance with claim 63 wherein thechambers of said cartridge include a plurality of fingers for releasablyholding said fastening means.
 66. The method in accordance with claim 64wherein said fasteners are hex-head screws.
 67. The method in accordancewith claim 63 wherein said indexing means comprises a pawl means and apin means.
 68. A screw gun in accordance with claim 1 further comprisingmeans for automatically sliding said cartridge holder on said guidepost.